Final answer:
In the given scenario, Michael is using his legitimate power to promote Shea, a high performing marketing executive, to the position of an assistant marketing manager.
Step-by-step explanation:
In the given scenario, Michael is using his legitimate power.
Legitimate power is based on the official position that a person holds in an organization. In this case, Michael, as the founder of the company, has the authority to promote employees and make decisions regarding the company's operations. By promoting Shea to a higher position, Michael is exercising his legitimate power to reward high performers and improve the quality of work in his company.